How to size Water main gec?

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bgelectric

Senior Member
Would I use table 250.66 to size the gec to the water main entrance?
The building has one 600a service for apartments and one 400 a service for house panel.
 
Yes, you would use T250.66 unless it met one of the conditions in (A),(B) or (C).

250.66 Size of Alternating-Current Grounding Elec-
trode Conductor. The size of the grounding electrode con-
ductor at the service, at each building or structure where
supplied by a feeder(s) or branch circuit(s), or at a sepa-
rately derived system of a grounded or ungrounded ac sys-
tem shall not be less than given in Table 250.66, except as
permitted in 250.66(A) through (C)
Click to expand...
 
Would the termination point have to be a the first point of disconnect (service disconnect) or a subpanel (mdp)?
 
250.24 Grounding Service-Supplied Alternating-Current
Systems.
(A) System Grounding Connections. A premises wiring
system supplied by a grounded ac service shall have a
grounding electrode conductor connected to the grounded
service conductor, at each service, in accordance with
250.24(A)(1) through (A)(5).
(1) General. The grounding electrode conductor connection
shall be made at any accessible point from the load end
of the service drop or service lateral to and including the
terminal or bus to which the grounded service conductor is
connected at the service disconnecting means.
 
jumper said:
250.24 Grounding Service-Supplied Alternating-Current
Systems.
(A) System Grounding Connections. A premises wiring
system supplied by a grounded ac service shall have a
grounding electrode conductor connected to the grounded
service conductor, at each service, in accordance with
250.24(A)(1) through (A)(5).
(1) General. The grounding electrode conductor connection
shall be made at any accessible point from the load end
of the service drop or service lateral to and including the
terminal or bus to which the grounded service conductor is
connected at the service disconnecting means.
Click to expand...

This would include the GEC from the water main...?
 
infinity said:
It would include all GEC connections to the grounded service conductor, with a few exceptions of course. :)
Click to expand...
I'm currently wondering whether a common GEC is permitted for more than one service (which is another question for the OP'er, as to whether it is actually two services, or just one with multiple disconnecting means).

250.64(D) covers a single service with multiple disconnecting means and using a common GEC... but there don't seem to be anything regarding multiple services.
 
Smart $ said:
I'm currently wondering whether a common GEC is permitted for more than one service (which is another question for the OP'er, as to whether it is actually two services, or just one with multiple disconnecting means).

250.64(D) covers a single service with multiple disconnecting means and using a common GEC... but there don't seem to be anything regarding multiple services.
Click to expand...

What about 250.30(A)(6)?

(6) Grounding Electrode Conductor, Multiple Separately
Derived Systems. A common grounding electrode
conductor for multiple separately derived systems shall be
permitted. If installed, the common grounding electrode
conductor shall be used to connect the grounded conductor
of the separately derived systems to the grounding electrode
as specified in 250.30(A)(4). A grounding electrode
conductor tap shall then be installed from each separately
derived system to the common grounding electrode conductor.
Each tap conductor shall connect the grounded conductor
of the separately derived system to the common
grounding electrode conductor. This connection shall be
made at the same point on the separately derived system
where the system bonding jumper is connected.
 
jumper said:
What about 250.30(A)(6)?

(6) Grounding Electrode Conductor, Multiple Separately
Derived Systems. A common grounding electrode
conductor for multiple separately derived systems shall be
permitted. If installed, the common grounding electrode
conductor shall be used to connect the grounded conductor
of the separately derived systems to the grounding electrode
as specified in 250.30(A)(4). A grounding electrode
conductor tap shall then be installed from each separately
derived system to the common grounding electrode conductor.
Each tap conductor shall connect the grounded conductor
of the separately derived system to the common
grounding electrode conductor. This connection shall be
made at the same point on the separately derived system
where the system bonding jumper is connected.
Click to expand...
Again, not multiple services.
 
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